Patent GB-593682-A (GB)
Title: Improvements in or relating to calculating apparatus
IPC: G06F7/498
Filed: 1944-05-19
Abstract: 593,682. Calculating apparatus. NATIONAL CASH REGISTER CO. May 19, 1944, No. 9733. Convention date, March 20, 1940. [Class 106 (i)] A calculating machine comprises an impulse generator which produces electrical impulses corresponding to amounts to be entered and a totalizer for said impulses, the totalizer consisting of denominational groups of electronic devices. In the embodiment described, the electronic devices are gas-filled electric-dis-, charge tubes and the impulse generator is also built up from such tubes, General arrangement and operation. To start the machine, a main switch is closed, whereupon any amount standing on a reading- out device is automatically fed back into the totalizer. A reset/restore key is next depressed and a signal lamp lights to indicate that the machine is ready for operation. If it is desired to zeroize the totalizer and reading-out device, the reset/restore key is depressed a second time. Numeral keys are then depressed in accordance with an item to be added and a start key operated.' Each denominational bank of numeral keys controls a corresponding " I differential actuator or impulse generator which, upon depression of the start key, sends to the respective denomination of the totalizer a number of impulses corresponding to the depressed digit key. The machine shown has two denominations on the keyboard and three in the totalizer. Keyboard. The digit keys 66, Fig. 2, are urged upwards by springs 70, but are retained in depressed condition by a latch bar 75 urged to the left by a spring 77 to engage a notch 78 in the stem of the depressed key. As a key is depressed, a cam on the stem moves the latch bar to the right to release any other key in that denomination. A transverse web of insulating material is fixed to each key-stem and carries four contacts 82 (two only are seen in Fig. 2). When the key is in raised position, each contact closes a corresponding circuit. When the key. is depressed, these four circuits are broken and the contacts complete four other circuits. Key releasing. After the item has been set on the keyboard, a start key 100, Figs. 6, 7, is depressed to cause entry into the totalizer. A solenoid 261 then becomes energized to rock a lever 263 to push the bar 75 of the units denomination to the right to release the numeral key. A second solenoid 262 simultaneously operates the tens-key latch bar. The operation of the solenoids 261, 262 is controlled by a gasfilled electric discharge device 155 common to both denominations and called the control tube. The grid 267 of the control tube 155 is normally maintained by connection with a supply line 95 at a negative potential sufficient to prevent the tube firing. When the start key is operated, positive impulses are generated in the manner described below by the firing of the gas-filled electric discharge tubes forming the impulse emitter. If e.g. the " 70 " digit key, Fig. 6, is in depressed condition, the impulse from the " 70 " discharge device is sent through switch 161 and a line 152, Fig. 7, to the control tube grid 267 whereby this tube is fired and current flows through its anode circuit from a source 91, closed start switch 100 and solenoid 149. The latter opens contacts 146 to shut down the impulse emitter and closes contacts 147 to energize the digitkey releasing solenoids 261, 262. Impulse generator. This comprises a gasfilled electric-discharge device 109, Figs. 6, 7, called a starting tube and nine similar devices or digit-impulse tubes 121, 128, for each denomination. Operation of the start key 100 after the depression of'digit keys (e.g. keys " 2 " in the units and " 7 " in the tens) applies a positive potential from a source 91 through digit-key-closed switch 104 and line 160 to the grid of the starting tube 109, causing this tube to fire. The positive potential is also applied from the source 91 through a line 144 to the anode 110 of the starting tube and, by switch 143 closed by the depressed digit key, to the anodes 122 of the digit-impulse tubes 121 up to and including that tube corresponding to the value of the depressed key.. The firing of the starting tube causes a current impulse to pass through a condenser 117 to the grid 119 of the " 1 " digit-impulse tube 121. This tube then fires and emits an impulse through a circuit containing a resistance 125 and condenser 135 in parallel into a units output conductor 150. The output conductor transmits the impulse to the totalizer. The end point 123 of resistance 125 is connected to the grid of the " 2 " digitimpulse tube 128 by a switch 164 closed because the " 1 " digit key is not depressed. The cathode of the " 2 " digit-impulse tube is connected to the other'end point 124 of the resistance 125. The condenser 135 keeps the points 123; 124 momentarily at the same voltage and the " 2 " digit-impulse tube thus does not fire immediately. When, however, a steady How is established through the "1" digit-impulse tube anode-cathode circuit and the resistance 125, the potential of point 124 and of the cathode 127 of the "2" digitimpulse tube falls and the latter fires. The resulting impulse is passed to the units output conductor 150 to send a second impulse to the totalizer and also to raise the potential of the cathode 120 of the " 1 " digit-impulse tube to extinguish this tube. The impulse is not, however, transmitted to the " 3 " digit tube, since the " 2 " key 62 is down and so switches the impulse to the conductor 152 connected by the switch 191 of the depressed " 70 " key in the tens denomination to the tens starting tube 154. This tube then fires and causes the successive firing of the first seven tens digitimpulse tubes. Seven impulses are thus sent through the tens output conductor 153 to the totalizer. The eighth tens tube is not, however, fired because the impulse from the seventh tube is diverted by the switch 161 into the conductor 152 to fire the control tube 155 to operate the key-releasing mechanism. In a modification, the tens part of the emitter is arranged to operate before the units part. Control circuits. " Ready " signal. Depression of the main switch key 90, Fig. 8, connects supply sources of appropriate voltage to terminals 91 ... 94 supplying the impulse emitter and to terminals 96, 97 supplying the totalizer. Potential is also supplied from source +170V through a line 402, contacts 403 and line 404 to a terminal 580 to cause the entry back into the totalizer of any amount which may be standing on the reading-out devices. A reset restore key 401 is then depressed to complete a circuit from the source +170V through the switch 401, line 433, contacts 413, gas-filled discharge tube 411 (which thereupon fires), cathode circuit 412 and solenoid 415 to earth. A solenoid-holding circuit is completed at contacts 420. The solenoid 415 opens the contacts 403 to break the circuit to the terminal 580 to disable the means causing entry back from the reading-out devices to the totalizer. Solenoid contacts 421 complete a circuit from a source +135V through a normally-closed switch 423 to a terminal 89 supplying the reading-out devices. The switch 423 can be opened to disable these devices by depressing a " non-indicate " key. The reset/restore key is now released and circuits are completed from the source + 170V, contacts 425, 422 to a terminal 98 connected to the totalizer transfer means and from contacts 422 to a second solenoid 424 provided with holding-circuit contacts 430. The second solenoid 424 closes contacts 429 to prepare a circuit such that if the reset/restore key is depressed a second time, potential is supplied from the source + 170V to a terminal 99 to zeroize the totalizer and reading-out devices. The second solenoid 424 also completes the circuit of a signal lamp 510 to indicate that the machine is ready for operation. Amplifying impulses between emitter and totalizer. An amplifier is provided at the input end of each denomination of the totalizer and as shown for. the units denomination, Fig. 9A, comprises a double-triode vacuum discharge tube 302. The first grid 301 is normally negatively biassed to prevent flow between anode 303 and cathode 305. The second grid 3] 3 is earthed so that current flows from anode 304 to cathode 306. Each impulse from the units output conductor is passed to a terminal 300 and thence to the first grid 301, causing a current surge from anode 303 to cathode 306. The resultant potential drop at point 317 is impressed on the second grid 313 to stop the anode current 304-306. This causes a potential impulse at point 319. Totalizer. Each denomination comprises ten digit-representing gas-filled electric-discharge devices (called digit-representing tubes) 331- 340, Figs. 9A-9C, and a similar transfer tube 341. The impulse produced at point 319 as explained above is impressed via a conductor 321 on the grids of all these tubes. When the main switch key 90, Fig. 8, is depressed, the potentials shown are applied to the terminals 96, 93, 97 and a tube, e.g. the " 5 " tube 336, corresponding to the digit shown by the reading- out device is fired as described below. The cathodes of the unfired tubes are maintained at - 32V and the grids at -110V. The cathode of the " 5 " tube, however, rises to +85V when this tube fires with the result that points 452, 453 and grid 522 of the " 6 " tube 337 rise to - 57V. The negative potential difference between the grid and cathode of " 6 " tube 337 is still too large to permit this tube to fire. When, however, an impulse is received in the line 321, the potential rise on the grids causes the " 6 " tube to fix, but is not sufficient to fire the,remaining tubes. The resulting rise in the voltage of the " 6 " cathode 521 causes cathode 393 of the " 5 " tube to rise momentarily above the anode voltage so that the " 5 " tube is extinguished. The grid of the " 7 " tube 338 rises to - 56V so that this latter tube is fired by the next impulse passe